It is proposed to study the role of cyclic AMP and cyclic GMP in nervous tissue. One approach is to study the effect of functional activity of the levels of cyclic AMP and cyclic GMP in various neural preparations. Another approach is to study dopamine-sensitive adenylate cyclase in the superior cervical ganglion since we believe that the dopamine-binding portion of this enzyme system is the dopamine receptor in the ganglion. A third approach is to purify and characterize from ganglionic tissue the enzyme believed to mediate the physiological effects of cyclic AMP in nervous tissue, namely cyclic AMP-dependent protein kinase.